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A traditional naval rank, lieutenant commander was once used in the old navies of Earth, among them the Royal Navy and the United States Navy. In these organizations, a lieutenant commander was a grade between the lieutenant and commander grades with the rank equivalent to a major in the marine or ground forces.

During the 23rd century, certain lieutenant commanders holding high shipboard positions, such as that of first officer, in a military tradition known as brevetting, were authorized to wear the full braid insignia of a commander while still retaining their rank of lieutenant commander. (TOS: "Court Martial", "The Menagerie, Part I")

In the 24th century Starfleet, lieutenant commander is an active rank with its close equivalents in alien militaries being the Cardassian rank of glinn and the Romulan rank of centurion. It is common in informal circumstances to refer to lieutenant commanders in Starfleet simply as "commander" by both those under their command and their commanding officers. Lieutenant commanders normally serve as senior department heads, executive officers on smaller vessels, and in some cases as starship commanders. Lieutenant commanders Tom Markel, Jadzia Dax, and Piersall all held commanding officer postings. It is worth noting that Jadzia Dax served as the commanding officer of the USS Defiant during the height of the Dominion War because she had acted as Captain Sisko's second in command and was the most qualified to take over for him when he had been reassigned to administrative duties at a starbase. However, her posting was temporary until the Captain returned to command a taskforce during Operation Return.

Spock, as well as a few other lieutenant commanders seen in The Original Series (such as Benjamin Finney), are very clearly called Lieutenant Commander while wearing the insignia of a Commander. While sometimes viewed as a costumer error, the late original series costume designer William Ware Theiss stated in interviews that this was very much deliberate and that the practice of Lieutenant Commanders wearing the insignia for a full Commander mirrored the US military concept of "brevet" or "spot" promotions given to officers due to the nature of their billets. In turn, Commander Chakotay wore the provisional rank insignia that was equivalent to a Lieutenant Commander (two "solid" bars and one "hollow" bar) throughout Star Trek: Voyager.

There have been four clear instances in Star Trek where a Lieutenant Commander was verbally addressed as "Lieutenant"; this being the case with Lieutenant Commander Elizabeth Shelby, who was called a Lieutenant in a briefing by Rear AdmiralJ.P. Hanson. Also, in three occasions, Lieutenant Commander Geordi La Forge was referred to as "Lieutenant," once by Tasha Yar in TNG: "Yesterday's Enterprise", once by Captain Picard in TNG: "The Most Toys" and by Data in TNG: "Hero Worship". While generally assumed that a script error led to these characters being called by the wrong rank, it is not beyond the realm of possibility that Starfleet protocol allows for the shortening of this rank to simply "lieutenant" in verbal conversation, much the same as Lieutenant Colonel is often shortened to "Colonel". Throughout Star Trek VI: The Undiscovered Country, Valeris wore Lieutenant Commander ranks (as well as a mismatched uniform department color), however she was only meant to be the rank of Lieutenant. This was due to a simple costume error and it was deemed too expensive to go back and reshoot the sequences with Valeris wearing the correct rank and uniform color so it was decided to just let it be. Tuvok was also incorrectly identified as Lieutenant after his promotion to Lieutenant Commander during his travels in the Delta Quadrant. While addressed as such in reference, not in person, in 2009's Star Trek, George Kirk wears Lieutenant Commander rank braids, but is referred to by Spock as "Lieutenant George Kirk" during his son's hearing a quarter-century later.

Many members of present day militaries which have this rank, however, shorten Lieutenant Commander to simply "Commander" in all but the most formal situations, since to address a Lieutenant Commander as a Lieutenant would appear disrespectful as this is a lower rank.

An issue of Star Trek: The Magazine established that the costuming department on Star Trek: Enterprise had no insignia for lieutenant commander. However, this does not mean the rank did not exist, merely that no on screen character had it and that no episode called for it. The rank was originally considered for use on the show with Malcolm Reed intended to be a lieutenant commander.

In Enterprise Season Four episode "Bound", Commander Tucker refers to his replacement "Kelby" as lieutenant despite him wearing three pips. This could possibly indicate that the rank existed with the same insignia as a full commander.